Video editing (Adobe premiere pro) help

[Aero512]

So i'm trying to put together clips from various streamers but most of them have different clip resolutions so some don't fit the screen. can someone help me out? here is an example of one that doesn't fit. https://i.imgur.com/u0VSB4C.jpg thanks

 

[Aero512]

even if i resize them it still doesn't fit perfectly.